http.clj

(ns qbits.jet.client.http
  (:refer-clojure :exclude [get])
  (:require
    [cheshire.core :as json]
    [clojure.core.async :as async]
    [clojure.core.async.impl.protocols :as protocols]
    [clojure.xml :as xml]
    [qbits.jet.client.ssl :as ssl]
    [qbits.jet.client.auth :as auth]
    [qbits.jet.client.cookies :as cookies]
    [qbits.jet.util :as util])
  (:import
    (clojure.lang
      Sequential)
    (java.net
      HttpCookie)
    (java.util.concurrent
      TimeUnit)
    (java.nio
      ByteBuffer)
    (java.nio.charset
      Charset)
    (java.io
      ByteArrayInputStream
      ByteArrayOutputStream
      IOException)
    (org.eclipse.jetty.client
      HttpClient
      HttpRequest
      HttpResponse)
    (org.eclipse.jetty.util
      Fields)
    (org.eclipse.jetty.client.util
      BytesContentProvider
      ByteBufferContentProvider
      DeferredContentProvider
      FormContentProvider
      InputStreamContentProvider
      MultiPartContentProvider
      PathContentProvider
      StringContentProvider)
    (org.eclipse.jetty.http
      HttpField
      HttpVersion)
    (org.eclipse.jetty.client.api
      Authentication$Result
      ContentProvider
      Request
      Request$FailureListener
      Response
      Response$AsyncContentListener
      Response$CompleteListener
      Response$HeadersListener)
    (org.eclipse.jetty.client.http
      HttpClientTransportOverHTTP)))

(def ^:const array-class (class (clojure.core/byte-array 0)))
(def default-buffer-size (* 1024 1024 4))
(def default-insecure-ssl-context-factory
  (delay (ssl/insecure-ssl-context-factory)))

(defn ^:no-doc ^array-class
  byte-buffer->bytes
  [^ByteBuffer bb]
  (let [ba (byte-array (.remaining bb))]
    (.get bb ba)
    ba))

(defn ^:no-doc byte-array->string
  [^bytes bb]
  (String. bb "UTF-8"))

(defn ^:no-doc decode-body [bb as]
  (case as
    :bytes bb
    :input-stream (ByteArrayInputStream. bb)
    :string (byte-array->string bb)
    :json (json/parse-string (byte-array->string bb) true)
    :json-str (json/parse-string (byte-array->string bb) false)
    :xml (xml/parse (ByteArrayInputStream. bb))
    (ByteBuffer/wrap bb)))

(defn fold-chunks+decode-xform [as buffer-size]
  (fn [reduction-function]
    (let [ba (ByteArrayOutputStream.)
          state (atom ::open)
          retrieve-data (fn [] (decode-body (.toByteArray ba) as))]
      (fn
        ([] (reduction-function))
        ([result]
         (when (compare-and-set! state ::open ::closed)
           (reduction-function result (retrieve-data))))
        ([result chunk]
         (.write ba chunk)
         (if (>= (.size ba) buffer-size)
           (let [data (retrieve-data)]
             (.reset ba)
             (reduction-function result data))
           (reduction-function result)))))))

(defn decode-chunk-xform
  [as]
  (fn [reduction-function]
    (fn
      ([] (reduction-function))
      ([result]
       (reduction-function result))
      ([result chunk]
       (reduction-function result (decode-body chunk as))))))

(defn- make-response
   [request ^Response response abort-ch body-ch error-chan trailers-ch]
   (let [headers (util/http-fields->map (.getHeaders response))
         status (.getStatus response)]
     {:abort-ch abort-ch
      :body body-ch
      :error-chan error-chan
      :headers headers
      :request request
      :status status
      :trailers (when (and (instance? HttpRequest request)
                           (util/trailers-supported? (some-> request .getVersion .asString) headers))
                  trailers-ch)}))

(defprotocol PRequest
  (encode-chunk [x])
  (encode-body [x])
  (encode-content-type [x]))

(extend-protocol PRequest
  (Class/forName "[B")
  (encode-chunk [x]
    (ByteBuffer/wrap x))
  (encode-body [ba]
    (BytesContentProvider. nil (into-array array-class [ba])))

  ByteBuffer
  (encode-chunk [x] x)
  (encode-body [bb]
    (ByteBufferContentProvider. nil (into-array ByteBuffer [bb])))

  java.nio.file.Path
  (encode-body [p]
    (PathContentProvider. nil p))

  java.io.InputStream
  (encode-body [s]
    (InputStreamContentProvider. s))

  String
  (encode-chunk [x]
    (ByteBuffer/wrap (.getBytes x "UTF-8")))
  (encode-body [x]
    (StringContentProvider. nil x (Charset/forName "UTF-8")))
  (encode-content-type [x]
    (str "Content-Type: " x))

  Number
  (encode-chunk [x] (encode-chunk (str x)))
  (encode-body [x] (encode-body (str x)))

  Sequential
  (encode-content-type [[content-type charset]]
    (str (encode-content-type content-type) "; charset=" (name charset)))

  clojure.core.async.impl.channels.ManyToManyChannel
  (encode-body [ch]
    (let [cp (DeferredContentProvider. (into-array ByteBuffer nil))]
      (async/go
        (loop []
          (if-let [chunk (async/<! ch)]
            (do (.offer ^DeferredContentProvider cp
                        (encode-chunk chunk))
                (recur))
            (.close ^DeferredContentProvider cp))))
      cp))

  Object
  (encode-chunk [x]
    (throw (ex-info "Chunk type no supported by encoder" {})))
  (encode-body [x]
    (throw (ex-info "Body type no supported by encoder" {})))
  (encode-content-type [content-type]
    (encode-content-type (subs (str content-type) 1))))

(defn ^:no-doc add-cookies!
  [^HttpClient client url cookies]
  (cookies/add-cookies! (.getCookieStore client)
                        url cookies))

(defn ^:no-doc add-auth!
  [^HttpClient client url {:keys [type user password realm]}]
  (.addAuthentication
   (.getAuthenticationStore client)
   (case type
     :digest (auth/digest-auth url realm user password)
     :basic (auth/basic-auth url realm user password))))

(defn ^HttpClient client
  ([{:keys [address-resolution-timeout
            client-name
            connect-timeout
            executor
            follow-redirects?
            max-redirects
            idle-timeout
            stop-timeout
            max-connections-per-destination
            max-requests-queued-per-destination
            request-buffer-size
            response-buffer-size
            scheduler
            user-agent
            cookie-store
            remove-idle-destinations?
            dispatch-io?
            tcp-no-delay?
            strict-event-ordering?
            ssl-context-factory
            transport]
     :or {remove-idle-destinations? true
          dispatch-io? true
          follow-redirects? true
          tcp-no-delay? true
          strict-event-ordering? false
          ssl-context-factory @default-insecure-ssl-context-factory
          transport (HttpClientTransportOverHTTP.)
          request-buffer-size default-buffer-size
          response-buffer-size default-buffer-size}
     :as r}]
   (let [client (HttpClient. transport ssl-context-factory)]

     (when address-resolution-timeout
       (.setAddressResolutionTimeout client (long address-resolution-timeout)))

     (when client-name
       (.setName client client-name))

     (when connect-timeout
       (.setConnectTimeout client (long connect-timeout)))

     (when max-redirects
       (.setMaxRedirects client (int max-redirects)))

     (when idle-timeout
       (.setIdleTimeout client (long idle-timeout)))

     (when max-connections-per-destination
       (.setMaxConnectionsPerDestination client (int max-connections-per-destination)))

     (when max-requests-queued-per-destination
       (.setMaxRequestsQueuedPerDestination client (int max-requests-queued-per-destination)))

     (when request-buffer-size
       (.setRequestBufferSize client (int request-buffer-size)))

     (when response-buffer-size
       (.setResponseBufferSize client (int response-buffer-size)))

     (when scheduler
       (.setScheduler client scheduler))

     (when user-agent
       (.setUserAgentField client (HttpField. "User-Agent" ^String user-agent)))

     (when stop-timeout
       (.setStopTimeout client (long stop-timeout)))

     (when cookie-store
       (.setCookieStore client cookie-store))

     (when executor
       (.setExecutor client executor))

     (.setRemoveIdleDestinations client remove-idle-destinations?)
     (.setDispatchIO client dispatch-io?)
     (.setFollowRedirects client follow-redirects?)
     (.setStrictEventOrdering client strict-event-ordering?)
     (.setTCPNoDelay client tcp-no-delay?)
     (.start client)
     client))
  ([] (client {})))

(defn stop-client!
  [^HttpClient cl]
  (.stop cl))

(defn- set-query-string!
  "Configures the query string in the request object directly."
  [^HttpRequest request query-string]
  (doto (.getDeclaredField HttpRequest "query")
    (.setAccessible true)
    (.set request query-string)))

(defn- track-response-trailers
  "Asynchronously loops and looks for presence of trailers in the response.
   Please see https://github.com/eclipse/jetty.project/issues/3842 for details on why we need this.
   When trailers are available, they are propagated to the trailers channel and the request input body is closed.
   The assumption is once trailers are available, the server is no longer interested in any of the request input data.
   We explicitly avoid closing the response body channel since this introduces a race in the asynchronous
   processing of any data streamed by the backend.
   Instead, closing the request content eventually triggers the response complete listeners after all the
   response bytes have been streamed."
  [response-trailers-ch response-body-ch content-provider-promise response]
  (async/go
    (let [trailer-interval-ms 1000]
      (loop []
        ;; iterate and check if trailers are available
        (async/<! (async/timeout trailer-interval-ms))
        (let [trailers (.getTrailers ^HttpResponse response)]
          (if trailers
            (do
              (async/>! response-trailers-ch (util/http-fields->map trailers))
              ;; close the input stream as server has already responded with a trailer
              (some-> content-provider-promise (deref 0 nil) (.close)))
            (when-not (protocols/closed? response-body-ch)
              (recur))))))))

(defn request
  [^HttpClient client
   {:keys [url method query-string form-params headers body trailers-fn
           content-type
           abort-ch
           accept
           as
           idle-timeout
           timeout
           agent
           follow-redirects?
           fold-chunked-response?
           fold-chunked-response-buffer-size
           ^Authentication$Result auth
           cookies
           multipart
           version]
    :or {method :get
         as :string
         follow-redirects? true
         fold-chunked-response? true
         fold-chunked-response-buffer-size Integer/MAX_VALUE}
    :as request-map}]
  (let [ch (async/promise-chan)
        error-ch (async/promise-chan)
        body-ch (async/chan 1
                            (if fold-chunked-response?
                              (fold-chunks+decode-xform as fold-chunked-response-buffer-size)
                              (decode-chunk-xform as)))
        trailers-ch (async/promise-chan)
        ^Request request (.newRequest client ^String url)
        trailers-supported? (and trailers-fn (instance? HttpRequest request))
        close-request-channels! (fn close-request-channels! []
                                  (async/close! error-ch)
                                  (async/close! body-ch)
                                  (async/close! trailers-ch)
                                  (when abort-ch
                                    (async/close! abort-ch))
                                  (async/close! ch))
        report-error! (fn report-error! [throwable]
                        (async/>!! ch {:error throwable})
                        (async/>!! error-ch {:error throwable}))
        content-provider-promise (promise)
        assign-content-provider! (fn assign-content-provider! [content-provider]
                                   (deliver content-provider-promise content-provider)
                                   content-provider)]

    (some->> version
      HttpVersion/fromString
      (.version request))

    (when abort-ch
      (async/go-loop []
        (when-let [abort-request (async/<! abort-ch)]
          (let [[cause callback] abort-request
                aborted? (.abort request cause)]
            (when callback
              (callback aborted?))
            (when aborted?
              (report-error! cause))
            (recur)))))

    (.followRedirects request follow-redirects?)

    (when timeout
      (.timeout request (long timeout) TimeUnit/MILLISECONDS))

    (when idle-timeout
      (.idleTimeout request (long idle-timeout) TimeUnit/MILLISECONDS))

    (when accept
      (.accept request (into-array String [(name accept)])))

    (when agent
      (.agent request agent))

    (.method request (name method))

    (when (seq form-params)
      (.content request
                (FormContentProvider. (let [f (Fields.)]
                                        (doseq [[k v] form-params]
                                          (.add f (name k) (str v)))
                                        f))))

       (when (seq multipart)
             (.content request
                       (let [provider (MultiPartContentProvider.)]
                            (doseq [[k v] multipart]
                                   (let [content (cond
                                                   (string? v) (StringContentProvider. v)
                                                   (instance? ContentProvider v) v
                                                   :else (throw (ex-info "Invalid multipart value" {k v})))]
                                        (.addFieldPart provider k content nil)))
                            (.close provider)
                            provider)))

    (do
      (when body
        (->> (encode-body body)
          (assign-content-provider!)
          (.content request)))
      (when trailers-supported?
        (.trailers ^HttpRequest request (util/trailers-fn->supplier trailers-fn))))

    (doseq [[k v] headers]
      (if (coll? v)
        (doseq [v' v]
          (.header request (name k) (str v')))
        (.header request (name k) (str v))))

    (when content-type
      (.header request "Content-Type" (name content-type)))

    (when auth
      (.apply auth request))

    (if (string? query-string)
      (set-query-string! request query-string)
      (doseq [[k v] query-string]
        (if (coll? v)
          (doseq [v' v]
            (.param request (name k) (str v')))
          (.param request (name k) (str v)))))

    (when cookies
      (doseq [[name value] cookies]
        (.cookie request (HttpCookie. name value))))

    (.onResponseContentAsync request
                             (reify Response$AsyncContentListener
                               (onContent [_ _ byte-buffer callback]
                                 (if (protocols/closed? body-ch)
                                   (let [ex (IOException. "Body channel closed unexpectedly")]
                                     (report-error! ex)
                                     (.failed callback ex)
                                     (.abort request ex))
                                   (async/put! body-ch (byte-buffer->bytes byte-buffer)
                                               (fn [_] (.succeeded callback)))))))

    (.onResponseHeaders request
                        (reify Response$HeadersListener
                          (onHeaders [_ response]
                            (async/put! ch (make-response request response abort-ch body-ch error-ch trailers-ch))
                            (when (util/http2-request? version)
                              (track-response-trailers trailers-ch body-ch content-provider-promise response)))))

    (.onRequestFailure request
                       (reify Request$FailureListener
                         (onFailure [_ _ throwable]
                           (report-error! throwable))))

    (.send request
           (reify Response$CompleteListener
             (onComplete [_ result]
               (when (not (.isSucceeded result))
                 (report-error! (.getFailure result)))
               (when-let [response (.getResponse result)]
                 (when (instance? HttpResponse response)
                   (when-let [trailers (.getTrailers ^HttpResponse response)]
                     (async/>!! trailers-ch (util/http-fields->map trailers)))))
               (close-request-channels!))))
    ch))

(defn get
  ([client url request-map]
   (request client
            (into {:method :get :url url}
                  request-map)))
  ([client url]
   (get client url {})))

(defn post
  ([client url request-map]
   (request client
            (into {:method :post :url url}
                  request-map)))
  ([client url]
   (post client url {})))

(defn put
  ([client url request-map]
   (request client
            (into {:method :put :url url}
                  request-map)))
  ([client url]
   (put client url {})))

(defn delete
  ([client url request-map]
   (request client
            (into {:method :delete :url url}
                  request-map)))
  ([client url]
   (delete client url {})))

(defn head
  ([client url request-map]
   (request client
            (into {:method :head :url url}
                  request-map)))
  ([client url]
   (head client url {})))

(defn trace
  ([client url request-map]
   (request client
            (into {:method :trace :url url}
                  request-map)))
  ([client url]
   (trace client url {})))